Grinding apparatus



Sept. 27, 1949. A. E. HAMILTON GRINDING APPARATUS Filed March 25, 1946 I INVENTOR ALf-fiffl HAM/1.70M

ATTORNEY Patented Sept. 27 1949 .UNlTED STAT-ES PATENTjOFFICE I Y 2Q4ss,279 [GR ND NG APrAIA'rUs 5 Alfred E. Hamilton, Pittsburgh, r A Application Marches, 194.6, Serial nol esavzs My invention relates to'grinding rolls for the surfacing of metal, wood, etc., and moreparticularly to rolls having drumsofthe pneumatic type that contain the abrasive or surfacin material nthe per pheralfacesj I, 7'

'Grinding apparatus of, this type frequently comprises one grinding roll or a pair of grinding rolls for surfacing strips or sheets of'material, each roll having a metal hub mounted on a, shaft and a pneumatic drum mounted on the hub and carrying the abrasive material, the abrasive material being contained on sleeves or on spirallye wound strips that surround the drum. p 7

My invention has for its object the provision of apparatus of the character referred to, wherein pneumatic pressure'is maintained at a desired predetermined degree, not only to provide the required or desired resistance by the pneumatic drum to grinding pressures, but which pressure is also utilized to releasably maintain the drum on. its hub and to hold the abrasive strips in place On the drum.

In the accompanying drawing, Figure 1 is a "6 (ila iin sg (01351 -192) view partly in' section and partly inelevation 7 showing a pair of rolls embodying my invention, and Fig. 2 is an enlarged sectional view through a portion of a pneumaticdruni and its hub. I; :j

The" numerals 4 'indicate" the' roll stand on which a pair of rolls 5 and 6 are supported by their respective shafts 1 and 8, the shafts being driven from a suitable source of power, by pulleys 9 and I0. As here shown, the rolls 5-6 are of identical construction and will grind or surface both sides of a strip or sheet that is passed between them. It will be understood that when only one face of a sheet is to be surfaced, a plainfaced billy roll can be substituted for the roll 6.

Since the rolls 5 and 6 are of identical construction, a description of the roll 5 will sufiice for both rolls. This roll 5 comprises a hollow hub portion ll of cylindrical contour whose end walls or plates are welded or otherwise secured to the shaft 7. Circular stiffening discs 12 are welded to the shaft 1 and to the inner peripheral surface of the hub, to stiffen the hub and permit the use of thinner gage metal for the hub.

A pneumatic drum l4 of rubber or other suitable elastic material is carried on the drum and has radially-spaced walls [5 and it that are joined at their ends, to provide a closed chamber 32 for the retention of air pressure within the drum. Helical strips I! of tough paper or cloth and having grit particles adhesively secured to their exposed surfaces are wound helically on the drum l4, their ends being suitably secured in place" thereon.v In the present instance, the strip endsare folded back as indicated at [9, the backturned ends being disposed between thehub and theinnermost peripheral surface of the drum and held there by reason of the air pressure in the drum. The helical turns of the strips are spaced apart perhaps one inch, at 2! to permit of some slight expansion or bulging of the drum at those areas (Fig. 2) and to thereby hold the strips against displacement axially of the drum. Also, the peripheral wall of the hub H is grooved as shown at 22 so, astoprovide an annular depression into which the, drum will be expanded under it'sinternal air pressure. This is for the purpose of-preventing endwiseshiftingjof the drum on the hub, and thus. avoid the necessity of providingi nd plates'or flanges on the ends of the hub to hold the drum in place thereon. A constant supplyofl'air pressure is maintained within the drum forjtherpurposeof giving a desired'resistancefor grinding .pressure and also toretain' the strips in place on the drum and to maintain the proper spacing between the helical turns. The pressure-supply system comprises a reservoir 23-,to which air under pressure is supplied by a pipe 24 leading from a suitable compressor or pump. Air from=the reservoir flows through a pressure-regulating valve 25 and past a relief valve 26, and through a pipe 21 which leads through a rotary joint or swivel coupling 28 into a bore in the shaft, and thence through a pipe 29 and a coupling 3! into the chamber 32 of the drum I l. The rotary coupling at 28 permits of maintaining a constant supply of air pressure during rotation of the roll.

The pressure regulator 25 is adjusted to give the desired pressure in the pneumatic drum,

while the relief valve 26 is adjusted to permit of exhaust of pressure from the drum in case the air therein is expanded to a pressure above that desired in the drum, which expansion may take place because of increase in atmospheric temperature, or may result from the heat of grinding friction. A similar pressure supply and relief system is provided for the roll 6, the pressureregulating valve being shown at 33 and the pressure-relief valve at 34, the air being conducted to the lower drum through a pipe 35. Where it is desired to have identical pressures in the upper and lower drums, a valve 35 in the line 39 will be closed and a valve 31 in a cross-connecting line 38 will be open, the pressure regulator 25 in that case serving for both drums.

In setting up the apparatus for a surfacing operation, the pneumatic drums are placed on 'single strip would sufiice, if made of adequate width and wrapped the required number of turns on the drum and with the proper helical pitch spacing.

I claim as my invention:

1. A grinding roll comprising a hub, a flexiblywalled drum on the hub, containing an abrasiveand having radially-spaced walls and end walls forming an annular-closed chamber, a depressed area in the periphery of the hub, and means for supplying air under pressure, to the interior of the drum, for expanding the innermost peripheral wall thereof into the said area.

2. A grinding roll comprising a hub, a flexiblywalleddrum on the hub, containing an abrasive and. having radially-spaced walls and endwalls forming an annular-closed chamber, a radially offset area at the periphery of the hub, and means for supplying air under pressure, to the interior of the drum, for expanding the innermost peripheral wall thereof into the said area, the said ofiset area being in the form of an annular groove in the periphery of the hub, intermediate the ends thereof. 7

3. A grinding roll comprising a hub, a flexiblywalled drum on the hub, having radially-spaced walls and end walls forming an annular-closed chamber, an abrasive=containing strip wrapped helically on the periphery of the drum, with its successive turns in spaced-apart relation, and means for supplying air under pressure to the interior of the drum,for expanding the outermost peripheral wall of the drum into the spaces between said helical turns. p

4. A grinding roll comprising a hub, a flexibly-- walled drum on the hub, having radially-spaced walls and end walls forming an annular closed chamber, an abrasive-containing strip wrapped helically on the periphery of the drum, with its successive turns in spaced-apart relation, means for supplying air under pressure to the interior of the drum, for expanding the outermost peripheral wall of the drum into the spaces between said helical turns, and means acted upon by said pressure, for gripping the ends of the strip to hold them in place against the drum.

A grinding roll comprising a hub, a flexiblywalled drum on the hub, having radially-spaced walls and end walls forming an annular-closed chamber, an abrasive-containing strip wrapped helically on the periphery of the drum, with its successive turns in spaced-apart relation, and

"i'neafisiioi 'siipplying air under pressure to the interior .of the drum, for expanding the outermost peripheral wall of the drum into the spaces between said helical turns, the ends of the strips being folded back between the drum and the hub wherebytheyare held in place by said air pressure. 1' 6. Agrinding' roll comprising a hub, a drum of elastic material carried by and surrounding the hub, a shouldered area on the peripheral surface of the drum, an abrasiveecontaining strip wrapped helically on the periphery of the drum, withsitsssuccessive turns in spaced-apart relation, and means for supplying air under pressure, to the ihterior of, the drum, for expanding the innermost and outermost walls of thevdrum, into ngagement with said shouldered area and into the spaces between said helical turns, respectively.

, ALFRED E. HAMILTON.-

REFERENCES CITED The following references are of record in the file of'this patent:

, UNITED STATES PATENTS Number Name Date 683,123 Knil1 Sept. 24, 1901 B lackett Feb- 15, 2,225,073 Miller r Dec. 17,- 1940 -"2,309,456 Hoskin et al.. Jan. 26,1943 2,323,962 Ames July 13, 1943 2.368.760 

